Tides

Question 1

What is a tide?

Answer 1

Tides are long-period waves that move through the oceans in response to the forces of the moon and sun.

• Tides originate in the oceans and progress toward the coastlines

Question 2

Why are tides ecologically important?

Answer 2

1. Create habitats (intertidal zone)
2. Mix upper water layer, nutrients and oxygen
3. Provide food for sedentary organisms
4. Disperse juvenile larval stages of marine organisms
5. Disperse pollutants from run-off

Question 3

Twin bulges in the planets water envelope are due to which two factors?

Answer 3

1. Inertia

2. Moon (gravitational attraction)

Question 4

What is the result of solar and lunar tides working synergistically together?

Answer 4

They create spring and neap tides.

Spring tides = The highest high and lowest low tides.

Neap tides = The lowest high and highest low tides.

Question 5

What are some reasons tides vary locally and globally?

think about movement of earth
the different forces 
pressure
winds
etc..

Answer 5

• Moon and sun
• Spring and neap tides
• Seasonal variation
• Declination
• Coriolis effect
• Depth (bathymetry)
• Low pressure
• Onshore winds

Question 6

What happens at aphidromic points or nodes in the ocean?

Answer 6

Amphidromic points = no tides at the node, but increasing tide with distance from node.

Question 7

What causes tides?

Answer 7

Gravity, mainly from the moon.

Question 8

Semidiurnal tides

Answer 8

2 high tides and 2 low tides per day

Question 9

Diurnal tides

Answer 9

1 high tide and 1 low tide per day

Question 10

Mixed semidiurnal tides

Answer 10

2 high and 2 low of different sizes each day